Wheel bearing apparatus for a vehicle

A vehicle wheel bearing apparatus comprising:

• an outer member formed with a body mounting flange on its outer circumference, the body mounting flange is to be mounted on a body of a vehicle, the outer member having an inner circumference including double row outer raceway surfaces;
• an inner member including a wheel hub and an inner ring or an outer joint member of a constant velocity universal joint, the wheel hub is formed at one end with a wheel mounting flange, the wheel hub having an outer circumference including one inner raceway surface opposing to one of the double row outer raceway surfaces, a cylindrical portion axially extending from the inner raceway surface, and the inner ring or outer joint member of a constant velocity universal joint being press-fit onto the cylindrical portion of the wheel hub and the inner ring or outer joint member outer circumference including an inner raceway surface opposing the other of the double row outer raceway surfaces;
• double row rolling elements freely rollably contained between the outer raceway surfaces of the outer member and the inner raceway surfaces of the inner member;
• seals mounted within annular openings formed between the outer member and the inner member;
• an inner side base portion of the wheel mounting flange is formed with a circular arc cross-section;
• a metal annulus mounted on the base portion is press-formed from a steel plate, the metal annulus further comprising a cylindrical fitting portion, a curved portion, a disk shaped portion, and an overhang portion, the cylindrical fitting portion fit onto a shoulder portion of the wheel hub, the curved portion formed with a circular arc cross-section that corresponds to a cross-sectional configuration of the base portion, the disk shaped portion extends radially outward from the curved portion and is in close contact with an inner side surface of the wheel mounting flange, and the overhang portion extends from a radially outermost portion of the disk shaped portion in a direction away from the wheel mounting flange;
• an elastic lip extends from the overhang portion of the metal annulus toward a side surface of the wheel mounting flange, the elastic lip elastically contacts the side surface of the wheel mounting flange with a desired contacting force via a predetermined interference, and an annular sealing space is formed between the elastic lip, wheel mounting flange and a connecting portion of the metal annulus, the annular sealing space positioned radially inward of the elastic lip;
• an outer side seal of the seals comprises a metal core and a sealing member, the metal core is fit into an inner circumference of an end of the outer member, the sealing member has side lips and a grease lip, the side lips slant radially outward, the grease lip slants radially inward toward the inner side of the bearing, the side lips and the grease lip slidingly contact the metal annulus;
• and
• the circular arc-cross section of the inner side base portion of the wheel mounting flange is formed with a radius of curvature “r”, the circular arc cross-section of the metal annulus is formed with a radius of curvature “R”, and the radii of curvature “r” and “R” are set with a relationship of R>r and a gap is formed between the inner side base portion and the metal annulus at the curved portion which prevents floating of the curved portion of the metal annulus from the base of the wheel mounting flange by interference of the curved portion of the metal annulus against the base portion of the wheel mounting flange, this forms a contact area between the side surface of the wheel mounting flange and the disk shaped portion of the metal annulus which suppresses variation of interference of the side lips to assure stable sealability.